This part of Texas is usually hot and dry during the summer. This past week we had a very unusual event: 7 days of rain. Every day we had some rain. Some days we had over 2 inches and other days we had an eighth or a quarter inch of rain. The total rain for the week was a bit over 6 inches. You might think this is a good thing. Not so – we had rain every day. Along with high humidity, we had very little sunshine to dry the leaves off. I went out to the garden a few times during the week and sprayed Neem oil on the leaves, but the rain every day just washed it off.
Before the week of rain, I had been battling powdery mildew, but the rain spread the stuff all over the garden. I can clearly see where the white stuff dripped to leaves below, to infect them. I can also see where it splashed around, spreading it thru rain drops.
This 8 Ball zucchini is totally infected with powdery mildew. This is rather unusual – these hybrid zucchini plants had showed themselves to be somewhat resistant to powdery mildew.
Here are some more zucchini plants that have a heavy, thick coating of powdery mildew. See how terribly thick those white spots are.
This squash plant is fatally infected with powdery mildew.
This yellow summer squash plant is just about dead from powdery mildew. All of the older leaves are fatally infected. There just isn’t enough plant left to support the growing tip – this plant will probably die before it produces another squash. It was a full, happy plant until the week of rain spread the mildew and killed the plant.
Another picture of powdery mildew all over zucchini leaves. The stuff is ALL OVER!
Look at these leaves – the powdery mildew is on every plant in the garden. It must have been spread by the rain that splattered all over the garden for a week.
These cucumber leaves seem fairly resistant to the powdery mildew blight, but the older leaves have some strange tan spots and holes in them. I don’t know what caused those holes.
The older leaves on these zucchini plants are totally destroyed and it has spread to the new growth. I sprayed the entire garden with Neem oil today, but most plants are t00 far gone to survive much longer. The powdery mildew is just too rampant.
All squash plants are affected, even the once resistant hybrid zucchini and Waltham butternuts. I have found out that Crenshaw squash are super- sensitive to powdery mildew.
This pic was taken before the rain week. It shows what powdery mildew does to leaves. A mild case of powdery mildew causes the leaves to become dry and stiff. They then dry out, develop holes and then die. This is the result of a mild case of mildew – after the week of rain I have a massive infection of powdery mildew. I can see it killing entire groups of leaves at a time.
I usually burn my old squash plants at seasons end – I do not put them in the compost if they show any sign of disease of bug infection. I’m not sure if powdery mildew will preclude my composting these plants. I really do need green plants in the compost, but I don’t want to risk feeding the compost pile an organism that may survive composting and spread next season. I’ll have to do some research on this matter.